1. Field of the Invention:
The present invention relates to a refrigerator containing a plurality of storage boxes vertically arranged, with prescribed space provided in a heat-insulating box and, more particularly, a refrigerator capable of separately controlling a storage temperature of each of the storage boxes.
2. Description of the Prior Art:
When preserving vegetables, fruit, meat, fish and other perishable foods (hereinafter referred to as the "foods") for a prolonged period of time at temperatures near freezing point in a refrigerator, or gradually thawing frozen foods, it is generally necessary to restrain a change in the refrigerator storage temperature as little as possible and to control to restrain the evaporation of water content from the foods.
In order to meet this need, there is preferably adapted a refrigerator of such a double-walled structure that storage boxes for storing foods are formed, through a required space defined between this heat-insulating box and the storage boxes, within a heat-insulating box which forms a refrigerating chamber, and a cold air is circulated from a evaporator into the space, thereby cooling the storage boxes.
The optimum refrigerating temperature differs with the kind of the foods, such as vegetables, fruit, meat and fish to be stored. Namely, for the prolonged preservation of the foods without deteriorating their freshness, it is essential to store the foods at their optimum refrigerating temperature. For this purpose, a plurality of storage boxes are formed in the heat-insulating box of the refrigerator of the double-walled structure, and each of the storage boxes is cooled to different storage temperature through a refrigeration system corresponding thereto, thereby enabling the most suitable storage of different kinds (the optimum refrigerating temperature varies) of the foods.
In this case, the refrigerator requires as many refrigeration systems as the storage boxes provided therein. This, however, has the drawback that the use of a large refrigerator including a larger number of storage parts will be demanded, resulting in a higher manufacturing cost. Moreover, there is such a drawback that because of the operation of a plurality of refrigeration systems, power consumption will increase.